Patent GB-834068-A (GB)
Title: Improvements in or relating to a motion picture projection system
IPC: G03B37/00
Filed: 1957-08-22
Abstract: 834,068. Kinematograph apparatus. NAKAMATSU, Y. Aug. 22, 1957 [Aug. 22, 1956; April 5, 1957], No. 26557/57. Class 97(1) A kinematograph film includes sequences of normal images mixed with sequences of anamorphosed images and, at the transition points, includes signal marks which control devices to change the optical projection system from normal to one for projecting enlarged images and to change the effective screen area to correspond. Fig. 1 shows a device for attachment to a projector 1 with lens 1<SP>1</SP> comprising a fixed reflector 3 and a pivoted reflector 2 movable by a motor M between a position in which the light beam emerges through an anamorphosing lens 4 and a position in which it is reflected through a normal lens 5 or through an aperture. The motor M (or 14) is controlled by the circuit shown in Fig. 3a. A roller 10, comprising metal discs insulated from each other bears on the film margin to which are attached metal foil contacts to mark the changes between normal and anamorphosed images. The metal foil connects the discs to close the circuits of relays 11, 12. The relay 11 energizes the motor 14 and a solenoid 13 which removes a latch 16 from a projection on the disc 17 to permit the disc to be rotated half a turn to move the mirror 2 between the two positions shown after which the circuit is opened. The relay 12 energizes a motor 15 which rotates screen elements 22, blackened on one side, through 180 degrees. The relay circuit is opened during the rotation but motor circuit is maintained by a moving contact 24 co-operating with fixed contacts 25 until the half turn is complete. The connection between the relay 12 and the motor circuit may be effected through a radio link. The screen elements 22 may be disposed (Fig. 4b) flanking a central screen area 20 so as to form an extended screen in one position but to be ineffective when their blackened faces are turned forward. In the form shown on Fig. 4d the elements 22, when turned blackened side outwards, form a mask for the central screen area 20. In a further form the motor 15 operates curtains to mask the marginal portions of the screen. Instead of contact strips on the film recorded signals may be used on a track which may be the normal sound track, in which case frequencies are used above or between the limits of the sound frequencies. The sound and control frequencies are distinguished by filters. Separate frequencies may be used for changing from large to small screen pictures and viceversa, or a continuously variable signal frequency may be used to produce corresponding speed variations in a motor driving a device with centrifugal masses the positions of which adjust the prisms of a double prism anamorphosing device. In one modification the mirror 2 (Fig. 1) is moved from the light path by sliding instead of pivoting. In another, the alternative lenses are brought into operation by rotation of a turret. In a further form a single objective is used but a movable mask is used to increase or decrease the portion of its field uitilized.